This invention relates generally to dental model trimming machines.
Modern dentistry often requires the preparation of cast plaster models of a patient's dental anatomy. These dental casts or models are used to study a patient's dental anatomy when fitting false teeth, braces, or engaging in other work. During the preparation of these plaster models, good practice requires grinding away part of each rough model or cast to provide relatively standardized facets or faces oriented generally parallel to the rows of teeth. Other facets or faces are provided at the heels or rear ends of the models in a plane at least generally parallel to the medial line of the cast tooth arch, and approximately equidistantly from the two rear molar casts.
These grinding or faceting operations are usually performed on a grinding machine or dental model trimming machine. Typically, a trimming machine includes an abrasive wheel and a work-supporting shelf adjacent the wheel upon which the model or cast is supported while the facets are being ground. Model orienting devices called angulators are often carried upon the work supporting shelf to engage the workpiece cast model and to precisely orient it in a predetermined angular position for grinding.
Extended use of the trimming machine inevitably wears out the abrasive on the abrasive wheel and requires its replacement. Until now, such replacement has been sometimes difficult, since many abrasive wheels are mounted directly to the hub of a motor shaft for relatively high speed rotation. Other model trimmers use rigid wheels permanently or semipermanently faced with an abrasive surface. Moreover, these wheels are surrounded by a housing adapted to retain groundaway grit, abraded plaster material and flushing or grinding fluids such as water. Thus, when it is desired to replace or change a grinding wheel or the face of a grinding wheel, the machine must be stopped, the housing disassembled, and the wheel removed or a new grinding face emplaced upon a backup wheel. Complex machine construction demands lengthy delays to accomplish this work.
Moreover, most prior machines provided only a single grinding face having a single grit size or a single abrasive quality. The abrasiveness of the grinding face was usually selected as a compromise between a coarse grinding grit providing rapid but coarse facet formation, and a find grinding grit providing slow but smooth and accurate facet formation. This compromise prevented rapid abrasive work for preliminary model forming, and further prevented relatively careful, slow final facet smoothing and finishing.
It is the general object of the invention to provide a model trimmer which will quickly trim dental models and provide model facets of high accuracy and quality.
A more specific object of the present invention is to provide an improved model trimming machine providing a plurality of different grinding surfaces mounted for common motion past a work station.
Another object is to provide a model trimmer wherein a grinding surface can be quickly and easily changed or replaced.
Yet another object is to provide a model trimmer having a substantially splash-free, substantially leak-free housing capable of accommodating copious amounts of cooling and flushing water.
Still another object is to provide a model trimmer having the above features in a compact yet rugged device of long service life and relatively maintenance-free, trouble-free operation.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. Throughout the description, like reference numerals refer to like parts.